I find telling recruiters my salary is a really bad idea. They then tell the company I am applying to what my salary is, which is a really shitty way to start off salary negotiations. I actually just don't work with recruiters anymore due to such a shitty experience.
Yeah my new rule of thumb is to avoid telling them what I make and try to tell them what it will take for me to leave my current position. I think I'm underpaid so I don't want to start by telling them how underpaid I am.
You can tell them a high target that would absolutely get your interest in the job. If it hits, great next step in your career. If it misses, no skin off your back.